1 “Starting in the name of Almighty Allah most merciful, most beneficent & most kind of all”

Abbas Research.pdf

Embed Size (px)

Citation preview

  • 1

    Starting in the name of Almighty Allah most merciful, most beneficent

    & most kind of all

  • 2

    Comparison of accommodation between myopes and emmetropes

    Among age group of 25 to 35 years



    B.Sc. (Hons) in Optometry & Orthoptics

    Submitted by Miss Zubia Sattar


    Supervisor Dr. Ali Raza

    M.B.B.S, M.C.P.S, F.C.P.S

    Course Coordinator Dr. Rasheed Shiekh


  • 3

    It is certified that Miss Zubia Sattar has completed her study on Comparison of

    accommodation between myopes and emmetropes among age group of 25 to 35 years for

    the partial fulfillment of the degree requirement of B.Sc. (Honors) Optometry & Orthoptics from

    Rawalpindi Medical College & Allied hospitals Rawalpindi.

    Dated: _____________ _____________________

    Signature of course supervisor

    Dr. Ali Raza

    M.B.B.S, M.C.P.S, F.C.P.S (Oph)

  • 4


    Starting under the shadow of ALLAHS blessing-The most merciful the most Gracious. I am

    thankful to Almighty Allah for wisdom, courage and perseverance that HE has bestowed upon

    me during accomplishment of this research.

    I would like to express my gratitude to my honorable coordinator Dr Rasheed whose stimulating

    suggestions and encouragement helped me to complete my research. A special thanks goes to

    Miss Saima who supervise me in whole duration with their full dedication and devotion. I would

    pay thanks to Miss Kashmala who helped me to correct my mistakes in practical work. I would

    also pay thanks to my husband Abbas Aslam for helping me a lot in making my results.

    Last but not the least I express my deep feelings to my respected parents and loving friends

    Attiya, Munam, Sadia, Rabia and Tayyaba for their support and encouragement.

    Zubia Sattar

  • 5


    I hereby declare that all the data during this study was collected by me

    and the data collection was used only for academic purpose.

  • 6


    Dedicated to my beloved parents

    Zubia Sattar

  • 7


    Purpose: The purpose of my study was to compare the accommodation between myopes and

    emmetropes among age group of 25 to 35 years.

    Material and Method: 99 subjects between ages of 25 to 35 years in eye OPD of Benazir

    Bhutto hospital were included in which there were 54 myopes and 45 emmetropes. Near point of

    convergence and amplitude of accommodation were measured with RAF rule. Different

    variables were also considered e.g. gender, visual acuity, cover test, and heishberg reflex test.

    Objective refraction (AR) and subjective refraction were performed for myopic patients and pen

    push up exercises were advice to convergence insufficiency patients.

    Results: Comparison showed that average amplitude of accommodation is higher in myopes

    than emmetropes.

    Conclusion: Study showed that amplitude of accommodation from 1-10D is more in myopes

    than emmetropes while amplitude of accommodation from 11-20D is more in emmetropes than

    in myopes. Accommodation amplitude 20-25D and 30-35D is also higher in myopes. Hence,

    myopic patients had more accommodation than emmetropes

  • 8













    Human eye

    Anatomy of human eye


    Mechanism of accommodation



    Relationship of accomodaton with emmetropia and myopia

    Literature review

    Rational of study

    Aim and Objective







    Study Design


    Duration of Study

  • 9







    Sample Size

    Sampling Technique

    Inclusion Criteria

    Exclusion Criteria


    Statistical Analysis











    4.1 References

  • 10








    Outdoor patient department



    Sine correction(without glasses)



    Cum correction(with glasses)



    Pin hole



    Near Point of Convergence



    Near Point of Accommodation



    Amplitude of Accommodation



    Cover test

  • 11

    Chapter 01


    1.1Human Eye

    The human eye is one of the most remarkable sensory systems. Leonardo da Vinci was acutely

    aware of its prime significance: the eye, which is termed the window of the soul, is the chief

    organ whereby the senso commune can have the most complete and magnificent view of the

    infinite works of nature [1]. Human beings gather most of the information about the external

    environment through their eyes and thus rely on sight more than on any other sense, with the eye

    being the most sensitive organ we have. Besides its consideration as a window to the soul, the

    eye can indeed serve as a window to the identity of an individual. It offers unique features for the

    application of identification technology.

    1.2 Anatomy of Human Eye

    The adult eyeball, often referred to as a spherical globe, is only approximately spherical in shape,

    with its largest diameter being 24 mm antero-posteriorly [2-3]. The anterior portion of the eye

    consists of the cornea, iris, pupil, and crystalline lens. The pupil serves as an aperture which is

    adjusted by the surrounding iris, acting as a diaphragm that regulates the amount of light entering

    the eye. Both the iris and the pupil are covered by the convex transparent cornea, the major

    refractive component of the eye due to the huge difference in refractive index across the air-

    cornea interface [4]. Together with the crystalline lens, the cornea is responsible for the

    formation of the optical image on the retina. The crystalline lens is held in place by suspensory

    ligaments, or zonules, that are attached to the ciliary muscle. Ciliary muscle actions cause the

    zonular fibers to relax or tighten and thus provide accommodation, the active function of the

  • 12

    crystalline lens. This ability to change its curvature, allowing objects at various distances to be

    brought into sharp focus on the retinal surface, decreases with age, with the eye becoming

    presbyopic. Besides the cornea and crystalline lens, both the vitreous and aqueous humor

    contribute to the dioptric apparatus of the eye, leading to an overall refractive power of about 60

    diopters [5]. The aqueous humor fills the anterior chamber between the cornea and iris, and also

    fills the posterior chamber that is situated between the iris and the zonular fibers and crystalline

    lens. Together with the vitreous humor, or vitreous, a loose gel filling the cavity between the

    crystalline lens and retina, the aqueous humor is responsible for maintaining the intraocular

    pressure and thereby helps the eyeball maintain its shape. Moreover, this clear watery fluid

    nourishes the cornea and crystalline lens. Taken all together, with its refracting constituents, self-

    adjusting aperture, and finally, its detecting segment, the eye is very similar to a photographic

    camera. The film of this optical system is the retina, the multilayered sensory tissue of the

    posterior eyeball onto which the light entering the eye is focused, forming a reversed and

    inverted image. External to the retina is the choroid, the layer that lies between retina and sclera.

    The choroid is primarily composed of a dense capillary plexus, as well as small arteries and

    veins [5]. As it consists of numerous blood vessels and thus contains many blood cells, the

    choroid supplies most of the back of the eye with necessary oxygen and nutrients. The sclera is

    the external fibrous covering of the eye. The visible portion of the sclera is commonly known as

    the white of the eye.

  • 13

    1.3 Accommodation

    Accommodation is increase in dioptric power of the eye when eye changes fixation from

    distance to near.

    As we know that in an emmetropic eye, parallel rays of light coming from infinity are brought to

    focus on the retina with accommodation at rest .Our eyes have been provided with the unique

    mechanism by which we can even focus the diverging rays coming from a near object on the

    retina in a bid to see clearly .This mechanism is called accommodation .In it, there occurs

    increase in the power of the crystalline lens. [6]

  • 14

    1.4 Mechanism of Accommodation

    Several theories have been proposed to explain the mechanism of accommodation of the human


    The more widely accepted Helmholtz theory of accommodation assumes that the zonules

    supporting the crystalline lens are under maximal tension when the lens is at minimum optical

    power.[7] The Helmholtz theory proposes that tension is exerted by the anterior and posterior

    zonules together or by all three sets of zonules simultaneously. This theory states that the optical

    power of the crystalline lens is increased by relaxation of the tension on these zonules, while an

    increase in zonular tension causes a decrease optical power.

    The Schachar theory of accommodation assumes that the equatorial zonules are under

    minimum tension when the lens is at minimum optical power [8-12] it states that the equatorial

    zonules apply increasing tension to the human crystalline lens during accommodation. This

    increased equatorial zonular tension increases the equatorial diameter of the lens, alters the

    surface curvatures of the human crystalline lens and, thereby, increases the central optical power

    of the lens. The Schachar theory proposes that during the accommodative process increasing

    tension is exerted exclusively by the equatorial zonules. In Schachars theory, the equatorial

    zonules act similar to skeletal muscle tendons and are the components that transduce the force of

    the ciliary muscle to change the shape and, thereby, the focal power of the crystalline lens. The

    anterior and posterior zonules act like the supportive ligaments of skeletal joints and are

    stabilizing components, which are tense during distance vision and relax during accommodation.

  • 15

    Hence, following are the changes occur during accommodation:

    Lens become more globular in shape

    Dioptric power of eye increases

    Pupil constricts

    Eyes converges

    Cilliary muscles contracts

    Zonules relaxes

    1.5 Emmetropia

    Emmetropia (optically normal eye) can be defined as a state of refraction wherein the parallel

    rays of light coming from infinity are focused at the sensitive layer of retina with the

    accommodation being at rest.

    Emmetropia describes the state of vision where an object at infinity is in sharp focus with the eye

    lens in a neutral or relaxed state. This condition of the normal eye is achieved when the refractive

    power of the cornea and the axial length of the eye balance out, which focuses rays exactly on

    the retina, resulting in perfect vision. An eye in a state of emmetropia requires no correction [13].

    1.6 Myopia

    Myopia or shortsightedness is a type of refractive error in which parallel rays of light coming

    from infinity focused in front of the retina when accommodation is at rest. . It is evident that

    during excessive near work, accommodation and convergence are continuously used. According

    to an international study, longer time spent on reading for pleasure and reports of close reading

  • 16

    distance (< 30 cm) were associated with a more myopic refraction[14]. The worldwide urban and

    rural patterns derived from both incidence and prevalence data are consistent with the near work

    hypothesis that increased reading and computer use may be a risk factor for myopia[15-16].

    The following diagram shows refraction of light in myopic eye.

    1.7 Relationship of accommodation with emmetropia and myopia

    Myopes are suspected to be poorer at responding to accommodative stimuli than emmetropes,

    and this may worsen the degree of their myopia. [17]

  • 17

    There is a strong association between myopia and near work, and it has been reported that the

    rapid rise in the prevalence of myopia in Singaporean children may be related to an increase in

    near work demands such as reading. [18-22]Although the mechanism by which near work affects

    myopia progression is not known, prolonged chronic accommodation during close work has been

    implicated in myopia. Supporting evidence for this theory provided by several researchers have

    demonstrated that myopic subjects tend to accommodate less to near targets, or that they

    exhibited a greater lag of accommodation than no myopic subjects. [23-25]

    1.8 Literature review

    Case 01:

    1.1 A study conducted in Sydney shows myopic eyes have reduced accommodative

    facility at distance, and accommodative responsiveness to both positive and negative

    defocus is slow. However, accommodative facility as a test does not have sufficient

    power to discriminate eyes with myopia from other refractive errors.

    Case 02:

    2.1 A study in England shows all accommodative behaviors have large inter-subject

    variability at all of the reading demands. Accommodative lags significantly increased

    with closer demands (Mean lag (D): 0.689D at 1.5D, 0.877D at 2.5D, 0.987D at 3.5D


  • 18

    Case 03

    3.1 A study conducted in United States shows eyes with lower amplitudes of

    accommodation must use more of their accommodative reserve for near work. Myopia

    may be an adaptation that develops in eyes with reduced accommodative amplitudes.

    1.9 Rational of the study

    In Pakistan to the best of my knowledge there are no published studies on relationship of

    accommodation between emmetropia and myopia.

    The present study aims to compare accommodation between emmetopes and myopes among age

    group 25-35 years.

    1.10 Aim and objective of the study

    To find out comparison of accommodation between myopes and emmetropes (25-35years)

    attending ophthalmology out-patient department at Benazir Bhutto Hospital Rawalpindi during the

    time period of three months.


    To find out amplitude of accommodation in myopes and emmetropes.

    To compare the amplitude of accommodation between myopes and emmetropes.

  • 19

    Chapter no.2

    2.1 Subject:

    Comparison of accommodation in myopes and emmetropes

    2.2 Study design:

    It was cross sectional descriptive study.

    2.3 Setting:

    Benazir Bhutto Hospital.

    2.4 Duration of study:

    Two months after the approval of synopsis.

    2.5 Sample size:

    99 subjects were selected depending upon the time available.

    2.6 Sampling technique:

    Consecutive sampling

    2.7 Inclusion criteria:

    Patients having age group of 25-35years.

    Patients of both sexes.

  • 20

    Patients having complained of headache.

    Patients with complain of blurred or decreased vision.

    Co-operative patients.

    2.8 Exclusion criteria:

    Traumatic eyes.

    Patients with ocular pathology.

    Patients with any systemic disease affecting eyes.

    Spherical corrections of more than 6.00 DS of myopia.

    Cylindrical correction of more than 0.75 DC

    Non Cooperative patients

    2.9 Study methodology:

    The study started on 1st November 2014 and continued till 1st January 2015. 99 subjects between

    ages of 25 to 35 years in eye OPD of Benazir Bhutto hospital were included in which there were

    54 myopes and 45 emmetropes .Visual acuity of all were taken by Snellens acuity chart at 6m.

    Objective refraction (AR) and subjective refraction were performed and pen push up exercises

    were advice to convergence insufficiency patients. Near point of convergence and amplitude of

    accommodation were measured with RAF rule after performing subjective refraction. Data was

  • 21

    collected on specially designed Performa under supervision of senior refractionists. Subjects

    having any ocular pathology other than refractive error were excluded from my study.

    2.10 Data analysis:

    All the data was analyzed using MS Excel 2010. Categorical data was represented by frequency,

    percentage and cross tabulation.

  • 22

    Chapter no. 3


    Total sample population was 99 out of which 50 were males and 49 were females.

    gender of subjects

    Frequency Percent Valid Percent



    Female 49 49.0 49.0 49.0

    Male 50 50.0 50.0 99.0

    Total 99 100.0 100.0

    Bar graph showing gender wise distribution of patients











    males females

    Series 1

    Series 1

  • 23

    Total Frequency of myopes and emmetropes:

    The results showed that myopia was present in 54 subjects (54.54%), and rest of 45(45.45%)

    were emmetropes out of 99.

    Frequency Percentage Cummulative













  • 24

    Bar chart showing frequency of myopes and emmetropes:










    myopes emmetropes

    Series 1

    Series 1

  • 25

    Gender wise distribution of myopia and emmetropia:

    In sample population of 99 there was 50 males out of which 20 were myopes and 30 were

    emmetropes while there were 49 females out of which 24 were myopic and 25 were emmetropes.













  • 26

    Graphical gender wise distribution of myopes and emmetropes








    myopia emmetropia



  • 27

    Accommodation in emmetropes and myopes * myopes

    and emmetropes Cross tabulation


    myopes and emmetropes

    Total myopes emmetropes


    Diopters) in

    emmetropes and


    1-5 10 4 14

    6-10 19 11 30

    11-15 12 17 29

    16-20 7 11 18

    21-25 4 0 4

    26-30 0 1 1

    31-35 2 1 3

    Total 54 45 99

  • 28

    Pie chart showing comparison of accommodation in myopes and emmetropes

  • 29


    Comparison of

    Accommodation in

    emmetropes and



    n in myopes


    in emmetropes

    N Valid 99 54 45

    Missing 0 45 54

    Mean 1.8283 11.54545 12.84118

    Std. Deviation

    Z test





    [Zcal] > 1.96 =Results are significant.


    The study was conducted to find out comparison of accommodation between myopes and

    emmetropes among age group 25-35y.Study showed that amplitude of accommodation from 1-

    10D is more is more in myopes than emmetropes while amplitude of accommodation from 11-

    20D is more in emmetropes than in myopes. Accommodation amplitude 20-25D and 30-35D is

    also higher in myopes. Z test showed that results are significant.

  • 30


    Results showed that overall average amplitude of accommodation is higher in myopes than in

    emmetropes. Myopic patients had more accommodation than emmetropes.


    Limitation of the study is small sample size.

    Limited resources.

    Short duration of study.

  • 31

    Chapter 04


    1. Pevsner, J.: Leonardo da Vincis contributions to neuroscience. Trends Neurosci. 25, 217220


    2. Davson, H.: The Eye, vol. 1a, 3rd edn. pp. 164. Academic Press, Orlando (1984)

    3. Born, A.J., Tripathi, R.C., Tripathi, B.J.: Wolffs Anatomy of the Eye and Orbit, 8th edn. pp.

    211232, 308 596. Chapman & Hall Medical, London (1997)

    4. Ian Hicksons Description of the Eye. http://academia.hixie.ch/ bath/eye/home.html. Accessed


    5. Warwick, R., Williams, P.L. (eds.): Grays Anatomy, 35th British edn. pp. 11001122. W.B

    Saunders, Philadelphia (1973)

    3) Christopher Candland, "Pakistans Recent Experience in Reforming Islamic Education" in

    Education Reform in Pakistan: Building for the Future, Washington, D.C. 2005: 151-153

    4) Abdullah Nowaira Khadija, Abdullah Tanveer Muhammad. Reaching out a strategy to provide

    primary eye care through the indigenous educational system in Pakistan. Community Eye Health

    J 2006; 19(59):52-53

    5)Ip JM, Saw SM, Rose KA, Morgan IG, Kifley A, Wang JJ, Mitchell P. Role of near work in

    myopia: findings in a sample of Australian school children. Invest Ophthalmol Vis Sci. 2008 Jul;


  • 32

    6) AK Khurana, (Ed.). (2008) Theory and Practice of Optics and Refraction. Reed Elsevier India

    Private Limited.

    7) von Helmholtz H. Uber die accommodation des auges. Albrecht von Graefes Arch

    Ophthalmol. 1855; 1:1-89.

    8) Schachar RA. Cause and treatment of presbyopia with a method for increasing the amplitude

    of accommodation. Ann Ophthalmol. 1992; 24:445-452.

    9) Schachar RA. Zonular function: A new hypothesis with clinical implications. Ann

    Ophthalmol. 1994; 26:36-38.

    10) Schachar RA, Anderson DA. The mechanism of ciliary muscle function. Ann Ophthalmol.

    1995; 27:126-132.

    11) Schachar RA. Histology of the ciliary muscle-zonular connections. Ann Ophthalmol. 1996;


    12) Schachar RA. Is Helmholtzs theory of accommodation correct? Ann Ophthalmol. 1999;


    13) Wikipedia, the free encyclopedia- Emmetropia

    14) Linn LK, Shih YF, Tsai CB, et al. Epidemiologic study of ocular refraction among school

    children in Taiwan in 1995. Optom Vis Sci1999; 76: 275-281

    15) Saw SM, Katz J, Schein OD, et al. Epidemiology of myopia. Epidemiol Rev. 1996;


    16) Ophthalmology. 2008 Apr; 115(4):678-685.e1.

    17) McBrien NA, Millodot MOphthalmic Physiol Opt. 1986; 6(2):145-9. [PubMed] [Ref list]

  • 33

    18) Saw SM, Chan B, Seenyen L, Yap M, Tan D, Chew SJ. Myopia in Singapore kindergarten

    children. Optometry 2001; 72:286-91.

    19) Saw SM, Wu HM, Seet B, Wong TY, Yap E, Chia KS, et al. Acade achievement, close up

    work parameters, and myopia in Singapore military conscripts. Br J Ophthalmol 2001; 85:855

    20)Saw SM, Hong RZ, Zhang MZ, Fu ZF, Ye M, Tan D, et al. Near-work activity and myopia in

    rural and urban schoolchildren in China. J Pediatric Ophthalmol Strabismus 2001; 38:149-55.

    21)Saw SM, Chua WH, Hong CY, Wu HM, Chan WY, Chia KS, et al. Near work in early-onset

    myopia. Invest Ophthalmol Vis Sci 2002; 43:332-9.

    22) Saw SM, Zhang MZ, Hong RZ, Fu ZF, Pang MH, Tan D. Near-work activity, night-lights,

    and myopia in the Singapore-China Study. Arch Ophthalmol 2002; 120:620-7.

    23) Abbott ML, Schmid KL, Strang NC. Differences in the accommodation stimulus curves of

    adult myopes and emmetropes. Ophthalmic Physio Opt 1998; 18:13-20.

    24) Gwiazda J, Thorn F, Bauer J, Held R. Myopic children show insufficient accommodative

    response to blur. Invest Ophthalmol Vis Sci 1993; 34:690-4.

    25) McBrien NA, Millodot M. The effect of refractive error on the accommodative response

    gradient. Ophthalmic Physiol Opt 1986; 6:145-9.

  • 34


    Patients Name: Age/ Gender: .


    Chief complain ..


    Ocular History ....................................

    Family Ocular History .

    Medical History ..

    Family Medical History .

    Contact lens History


    Slit lamp examination

    Lids ..

    Pupil .

    Cornea .


    Visual Acuity SCC CC PH

    Rt Eye: .. . ....

  • 35

    Lt Eye : . .

    Hirschberg reflex:Cover test ...................................................................


    1. Objective Refraction (Retinoscopy )

    Rt.Eye: .. Lt.Eye: ..

    2 Subjective Refraction

    Rt Eye: Lt Eye:

    Final Prescription:

    Rt. Eye: Lt. Eye: ...

    Type of refractive error: Myopia Hypermetropia Astigmatism

    Amblyopia Anisometropia

    Visual Acuity with glasses: Rt. Eye Lt. Eye

    Diagnosis: ____________________________________________________________________________________________



    _______________________________ _______________________________

    Sign of student sign of supervisor